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Announcements

Next week: Organizational Cloud discussion pros/cons

• Teams to revisit individual findings and

report Upcoming R2

APIs & Web Services

SWEN-343

Today

Need for APIs Webservices Types

SOAP & REST

SOA Microservices

API – (High-Level) Definition

Application Program Interface “A set of routines, protocols, and tools for building software applications. The API specifies how software components should interact.”

API Benefits

Efficiency: Create the “functions” once Integration: Components can work together much easier “Future Ready”: Faster & easier data migration Wider Reach: Allow a more diverse audience to use your tool/functionality

Play/Add/Analyze/Report /Subscribe/Stream Map/View/Interact/Estimate/ Calculate Distance/Geocode

Service Definition

• Discrete unit of software functionality with

the purpose of reuse by different clients.

• Includes the policies, constraints and

capabilities of its use.

• Remote access is provided using a

prescribed interface.

What is A Web Service

“The term Web Services describes a standardized way of integrating Web-based applications using open standards over an Internet protocol backbone.”

Web Service

A web service is different from a web application

• A web application is for use by

humans

Such as http://www.weather.com

• A web service is for use by

programs

Such as Twitter APIs:

https://dev.twitter.com/rest/reference/get/followers/ids

Web Service

Provides application components and interoperable machine-to-machine interaction Self-contained and self-described in a machine- processable format (such as WSDL). Can be published, found, and used on the Web Communicate using open protocols: SOAP messages using HTTP and XML/JSON serialization and other web-related standards. Cross platform compatible

Web Service Benefits

Allow different applications from different sources to communicate with each other

• Internal & external

Not tied to any one operating system or programming language. Secure access to data Web services can tightly control access to the data and services they make available to other applications.

WS Design Patterns

Facade Proxy Others….

WEB Service API (Styles and impls)

• RPC API
• Message API
• Resource API
• SOAP
• REST
• Microservices

SOAP & REST

ACID

• Atomicity. In a transaction involving two or more discrete pieces of information, either all
• f the pieces are committed or none are.
• Consistency. A transaction either creates a new and valid state of data, or, if any failure
• ccurs, returns all data to its state before the transaction was started.
• Isolation. A transaction in process and not yet committed must remain isolated from any
• ther transaction.
• Durability. Committed data is saved by the system such that, even in the event of a

failure and system restart, the data is available in its correct state.

ACID (Atomicity, Consistency, Isolation, Durability)

Web Services: SOAP & REST

SOAP = Protocol, REST = Architecture SOAP: Heavier weight Tightly coupled to server Supports: ACID transactions ACID = Ensure reliable transactions Adds some security features REST: Lighter & Simpler No UDDI Not restricted to XML

Web Services: SOAP & REST

SOAP: Standards-based Web Services access protocol Been around a while Pushed by MS REST Not so “new” kid on the block Simple method of accessing web services Both use HTTP protocol

SOAP Based WS Components

• 1. SOAP: XML-based protocol for exchanging information

between computers.

• 2. WSDL: XML-based language for describing web services

and how to access them.

• 3. UDDI: XML-based standard for describing, publishing, and

finding web services

a. UDDI= UDDI (Universal Description, Discovery, and Integration) - XML based registry. i. Defines a way to publish and discover information about Web services. b. Now mostly used inside companies

SOAP Web Service Components

Simple Object Access Protocol (SOAP)

Foundation layer of WS Protocol stack Components: Envelope: Defines message structure Encoding rules Convention for procedure calls & responses

Representational state transfer (REST)

“An architectural style, and an approach to communications that is often used in the development of Web services.”

RESTful API

Breaks down transactions to create series of small modules = → flexibility PUT: Change state of or update resource GET: Retrieve Resource PATCH DELETE

Service Oriented Architecture

Service Oriented Architecture (SOA)

An approach used to create an architecture based upon the use

• f services.

Services (such as RESTful Web services) carry out some small function, such as producing data, validating a customer, or providing simple analytical services. A primary goal is loose coupling SOA Service:

• logically represents a business activity with a specified outcome.
• self-contained.
• is a black-box for its consumers.
• may consist of other underlying services.

SOA

Does not necessarily require Web Services Build a system from autonomous services Integration is forethought, not afterthought May combine different: Languages Platforms Security models Business Processes And this is ok!

How SOA Works

http://www.mainsysgroup.com/sites/default/files/mainsys/Architecture-FRONTeO-E-banking%20- %20ColRev2_0.jpg

SOA meta-model, The Linthicum Group

SOA - Myths & Facts

SOA is a technology SOA is a design philosophy independent of any vendor, product, technology or industry trend. SOAs require Web Services SOAs may be realized via Web services but Web services are not necessarily required to implement SOA SOA requires a complete technology and business processes overhaul SOA should be incremental and built upon your current investments We need to build a SOA SOA is a means, not an end

SOA - Reuse

Connect into what is already there - Layer business process management, collaborative workflows, and reporting on top

• f existing IT assets.

Extract more value from what is already there - Enable existing applications to be reused in new ways. Extend and evolve what we already have - Create IT support for new cross-functional business processes that extend beyond the boundaries of what the existing applications were designed to do.

Recap

What are the difference between SOAP & REST? Primary goals of SOA What technologies are used in SOA?

Activity

Investigate, summarize, submit, present

API Best Practices External API 3rd party services OpenAPI MicroServices Micro/Transactions ACID in RDBMS

Microservices

Read about Microservices [1], [2] Understand

What are they? Benefits? Drawbacks? Where are they used?

Could/should you use it in your project? Have/Will you use it in your project?